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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
September 2008
FAN400A -- Low-Power Green-Mode PWM Flyback Power
Controller without Secondary Feedback
Features
Linearly Decreasing PWM Frequency Green Mode Under Light-Load and Zero-Load Conditions Constant Voltage (CV) and Constant Current (CC) No Secondary Feedback Low Startup Current: 8A Low Operating Current: 3.6mA Leading-Edge Blanking Constant Power Limit Universal AC Input Range Synchronized Slope Compensation 140C OTP Sensor with Hysteresis VDD Over-Voltage Clamping Cycle-by-Cycle Current Limiting Under-Voltage Lockout (UVLO) Fixed PWM Frequency with Hopping Gate Output Maximum Voltage Clamped at 17V Small SSOT-6 Package
Description
This highly integrated PWM controller provides several features to enhance the performance of low-power flyback converters. To minimize standby power consumption, a proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load and zero-load conditions. This green mode enables the power supply to meet international power conservation requirements. The supply voltage VDD is also used for feedback compensation, to regulate the output voltage without requiring a conventional TL431 and a photo-coupler. Another advantage of the FAN400A is that the typical startup current is only 8A, while the typical operating current can be as low as 3.6mA. A large startup resistance can be used to achieve even higher power conversion efficiency. FAN400A integrates a frequency hopping function internally to reduce EMI emissions with minimum line filters. Built-in synchronized slope compensation maintains the stability of peak current-mode control. Proprietary internal compensation ensures constant output power limiting over a universal range of AC input voltages, from 90VAC to 264VAC. The FAN400A provides many protection functions. Pulse-by-pulse current limiting ensures constant output current, even if a short circuit occurs. The internal protection circuit disables PWM output if VDD exceeds 22.7V. The gate output is clamped at 17V to protect the power MOS from over-voltage damage. The built-in over-temperature protection (OTP) function shuts down the controller at 140C with a 30C hysteresis. The FAN400A is designed to provide a low-cost total solution for flyback converters. It is available in a smallfootprint, 6-pin, SSOT-6 package.
Applications
General-purpose, switching mode, power supplies and flyback power converters, such as: Battery Chargers for Cellular Phones, Cordless Phones, PDAs, Digital Cameras, Power Tools Power Adapters for Ink Jet Printers, Video Game Consoles, Portable Audio Players Open-Frame SMPS for TV/DVD Standby and Auxiliary Supplies, Home Appliances, Consumer Electronics Replacement for Linear Transformers and RCC SMPS PC 5V Standby Power
Related Resources
AN-400A Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Ordering Information
Part Number
FAN400ATY FAN400ANY
Operating Temperature Range
-40C to +105C -40C to +105C
Package
SSOT-6 DIP-8
Eco Status
Green Green
Packing Method
Tape & Reel Tube
For Fairchild's definition of "green" please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1 www.fairchildsemi.com
FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Application Diagram
V IN
R IN D1
DO CO W AU X VO
VDD G ATE
Q1
C IN
S EN SE GN D
RS
Figure 1.
Typical Application
Internal Block Diagram
Figure 2.
Functional Block Diagram
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Marking Information
XXX: AAT=FAN400A TT : Die run code
. . . : Year code
- - - : Week code
1'st line Z: Assembly plant code X: Year code Y: Week code TT: Die run code 3'rd line T: N=DIP P: Y=Green package M: Manufacture flow code Figure 3. Top Mark
Pin Configuration SSOT-6 GND FB NC GATE VDD SENSE
Figure 4.
DIP-8 GATE VDD NC SENSE
Pin Configurations
GND FB NC NC
Pin Definitions
DIP Pin #
1 2 3 4 5 6 7 8 3 2 1 4
SSOT Pin #
6 5
Name
GATE VDD NC SENSE NC NC FB GND
Description
The totem-pole output driver to drive the power MOSFET Power supply No connection Current sense senses the voltage across a sensed resistor. To provide overcurrent protection, PWM output is disabled if the voltage exceeds an internal threshold. This pin also provides current information for current-mode control. No connection No connection The FB pin provides feedback information to the internal PWM comparator. This feedback is used to control the duty cycle. When no feedback is provided, this pin is left open. Ground
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Absolute Maximum Ratings
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only.
Symbol
VVDD VFB VSENSE TJ JA TSTG TL ESD DC Supply Voltage
(1, 2)
Parameter
Input Voltage to FB Pin Input Voltage to Sense Pin Operating Junction Temperature Thermal Resistance (Junction-to-Air) Storage Temperature Range Lead Temperature (Wave Soldering or IR, 10 Seconds) Electrostatic Discharge Capability Human Body Model JESD22-A114 Machine Model JESD22-A114 SSOT DIP
Min.
-0.3 -0.3
Max.
30 7.0 7.0 +150 263.3 135.7
Unit
V V V C C/W C/W C C kV V
-55
+150 +260 4 200
Notes: 1. All voltage values, except differential voltages, are given with respect to GND pin. 2. Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device.
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Electrical Characteristics
Unless otherwise noted, VDD=15V and TA=25C.
Symbol VDD Section
VDD-OP VDD-ON VDD-OFF IDD-ST IDD-OP VDD-G OFF
Parameter
Conditions
With Secondary Feedback Without Secondary Feedback
Min.
Typ.
Max.
Units
20 22.7 16 7.5 17 8.0 8 3.6 VDD-OFF+1.2 18 8.5 20 4.6
V V V V A mA V
Continuously Operation Voltage
Turn-on Threshold Voltage Turn-off Threshold Voltage Startup Current Operating Supply Current VDD Low-threshold Voltage to Exit Green-off Mode Input-Voltage to Current-Sense Attenuation Input Impedance Open-Loop Voltage VDD Feedback Threshold Voltage FB is Open IFB=0.4mA IFB=0.1mA to 0.2mA VDD=VDD-ON - 0.1V CL=1nF
Feedback Input Section
AV ZFB VFB-OPEN VDD-FB 2/5 2.4 4.5 20.7 18.4 22.7 20.4 100 VDD=18V VSTHVA Current Limit Valley Threshold Voltage VDD=15V VDD=10V VDD=18V VSTHFL tLEB Current Limit Flat Threshold Voltage Leading-Edge Blanking Time VDD=15V VDD=10V 250 0.81 0.73 0.58 1.10 1.01 0.81 310 370 24.7 22.4 150 V/V k V V V ns V V V V V V ns
Current-Sense Section
tPD Propagation Delay
Figure 5.
Saw Limit
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Electrical Characteristics (Continued)
Unless otherwise noted, VDD=15V and TA=25C.
Symbol Oscillator Section
fOSC tHOP fOSC-G VFB-N VFB-G VFB-Z SG fDV fDT DCYMAX VGATE-L VGATE-H tr tf VGATECLAMP
Parameter
Center Frequency Hopping Range
Conditions
Min.
60 4.1 14.5 2.3
Typ.
65 4.6 4 17.0 2.6 VFB-N 0.75 1.4
Max.
70 5.1 19.5 2.9
Units
Frequency Hopping Period Green Mode Frequency
kHz ms KHz V V V
Green Mode Entry FB Voltage Green Mode Ending FB Voltage Zero Duty Cycle FB Voltage Green Mode Modulation Slope Frequency Variation vs. VDD Deviation Frequency Variation vs. Temperature Deviation Maximum Duty Cycle GATE Low Voltage GATE High Voltage GATE Rising Time GATE Falling Time GATE Output Clamping Voltage IO=10mA IO=-10mA CL=1nF CL=1nF VDD=20V VDD=10 to 22V TA=-20 to 85C
40
70 1.5
100 2 5.0 78 1.5
Hz/mV % % % V V ns ns V
Output Section
68 8 150 70 16 200 90 17 250 110 18 73
Over Temperature Protection (OTP)
TOTP TOTPRESTART
Protection Junction Temperature Restart Junction Temperature
140 110
C C
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Typical Performance Characteristics
17
8.6
16.8
8.4
V DD-OFF (V)
-40 -25 -10 5 20 35 50 65 80 95 110 125
V DD-ON (V)
16.6
8.2
16.4
8
16.2
7.8
16
7.6 -40 -25 -10 5 20 35 50 65 80 95 110 125
T emperature ( )
T emperature ( )
Figure 6.
Turn-on Threshold Voltage (VDD-ON) vs. Temperature
Figure 7.
Turn-off Threshold Voltage (VDD-ON) vs. Temperature
9
4
8
3.8
7
IDD-OP (mA)
-40 -25 -10 5 20 35 50 65 80 95 110 125
IDD-ST (A)
3.6
6
3.4
5
3.2
4
3 -40 -25 -10 5 20 35 50 65 80 95 110 125
T emperature ( )
T emperature ( )
Figure 8.
Startup Current (IDD-ST) vs. Temperature
Figure 9.
Operating Supply Current (IDD-OP) vs. Temperature
68 67
75
74
DCY MAX (%)
fOSC (KHz)
66 65 64 63 62 -40 -25 -10 5 20 35 50 65 80 95 110 125
73
72
71
70 -40 -25 -10 5 20 35 50 65 80 95 110 125
T emperature ( )
T emperature ( )
Figure 10.
Center Frequency (fOSC) vs. Temperature
Figure 11.
Maximum Duty Cycle (DCYMAX) vs. Temperature
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Typical Performance Characteristics
3 2.2
2.8
2
V FB-N (V)
2.6
V FB-G (V)
-40 -25 -10 5 20 35 50 65 80 95 110 125
1.8
2.4
1.6
2.2
1.4
2
1.2 -40 -25 -10 5 20 35 50 65 80 95 110 125
T emperature ( )
T emperature ( )
Figure 12.
Green-Mode Entry FB Voltage (VFB-N) vs. Temperature
Figure 13.
Green-Mode Ending FB Voltage (VFB-G) vs. Temperature
300
5 4.5 4 3.5 3 2.5 2 -40 -25 -10 5 20 35 50 65 80 95 110 125 12 13 14 15 16 17 18 19 20 21 22 23 24
280
tLEB (ns)
260
240
220
200
IDD-OP (mA)
Temperature ( )
V DD (V)
Figure 14.
Leading-Edge Blanking Time (tLEB) vs. Temperature
Figure 15.
Operating Supply Current vs. VDD Voltage
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Operation Description
FAN400A devices integrate many useful functions for low-power switch-mode power supplies. The following descriptions highlight the key features of the FAN400A.
Oscillator Operation
The oscillation frequency is fixed at 65KHz.
Startup Current
The required startup current is only 8A. This allows a high-resistance, low-wattage startup resistor to supply the controller's startup power. A 1.5 M/0.25W startup resistor can be used over a wide input range (100V240VAC) with very little power loss.
Leading-Edge Blanking (LEB)
Each time the power MOSFET is switched on, a turn-on spike occurs at the sense-resistor. To avoid premature termination of the switching pulse, a 310ns leadingedge blanking time is built in. Conventional RC filtering is not necessary. During this blanking period, the current-limit comparator is disabled and cannot switch off the gate drive.
Operating Current
The operating current is normally 3.6mA, which results in higher efficiency and reduces the required VDD holdup capacitance. A 10F/25V VDD hold-up capacitor can be used over a wide input range (100V-240VAC) with very little power loss.
Constant Output Power Limit
When the SENSE voltage across the sense resistor RS reaches the threshold voltage (around 1.0V), the output GATE drive is turned off following a small propagation delay, tPD. This propagation delay introduces an additional current proportional to tPD*VIN/LP. The propagation delay is nearly constant regardless of the input line voltage VIN. Higher input line voltages result in larger additional currents. Under high input-line voltages the output power limit is higher than under low input-line voltages. Over a wide range of AC input voltages, the variation can be significant. To compensate for this, the threshold voltage is adjusted by adding a positive ramp (Vlimit_ramp). This ramp signal can vary from 0.73V to 1.01V and flattens out at 1.01V. A smaller threshold voltage forces the output GATE drive to terminate earlier, reducing total PWM turn-on time and making the output power equal to that of the low line input. This proprietary internal compensation feature ensures a constant output power limit over a wide range of AC input voltages (90VAC to 264VAC).
Green-Mode Operation
The proprietary green-mode function provides off-time modulation to linearly decrease the switching frequency under light-load and zero-load conditions. The on-time is limited to provide better protection against brownouts and other abnormal conditions. Power supplies using the FAN400A can meet international restrictions regarding standby power-consumption.
Constant Voltage (CV) and Constant Current (CC) without Feedback
The FAN400A can tightly regulate the output voltage and provide over-current protection without requiring secondary-side feedback signals. For improved CV and CC accuracy, the transformer leakage inductance should be reduced as much as possible.
Under Voltage Lockout (UVLO)
The turn-on/turn-off thresholds are fixed internally at 17V and 8V. To enable the FAN400A during startup, the hold-up capacitor must first be charged to 17V through the startup resistor. The hold-up capacitor continues to supply VDD before energy can be delivered from the auxiliary winding of the main transformer. VDD must not drop below 8V during this startup process. This UVLO hysteresis window ensures that the hold-up capacitor can adequately supply VDD during startup.
Over-Temperature Protection (OTP)
The FAN400A has a built-in temperature sensing circuit to shut down PWM output once the junction temperature exceeds 140C. While PWM output is shut down, the VDD voltage gradually drops to the UVLO voltage. Some of the internal circuits are shut down, and VDD gradually starts increasing again. When VDD reaches 17V, all the internal circuits, including the temperature sensing circuit, operate normally. If the junction temperature is still higher than 140C, the PWM controller shuts down immediately. This situation continues until the temperature drops below 110C. The PWM output is then turned back on. The temperature hysteresis window for the OTP circuit is 30C.
Gate Output
The BiCMOS output stage is a fast totem-pole gate driver. Cross-conduction is avoided to minimize heat dissipation, increase efficiency, and enhance reliability. The output driver is clamped by an internal 17V Zener diode to protect the power MOSFET transistors against any harmful over-voltage gate signals.
VDD Over-Voltage Clamping
VDD over-voltage clamping is built in to prevent damage from over-voltage conditions. When VDD exceeds 22.7V, PWM output is shut down. Over-voltage conditions may be caused by an open photo-coupler loop or a short circuit in the output.
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Operation Description (Continued)
Slope Compensation
The sensed voltage across the current sense resistor is used for current mode control and pulse-by-pulse current limiting. The built-in slope compensation improves power supply stability. Furthermore, it prevents sub-harmonic oscillations that normally would occur because of peak current mode control. A positively sloped, synchronized ramp is activated with every switching cycle. The slope of the ramp is: 0.33 x Duty (1) Duty(max.)
Noise Immunity
Noise from the current sense or the control signal may cause significant pulse-width jitter, particularly in continuous-conduction mode. Slope compensation helps alleviate this problem. Good placement and layout practices should be followed. The designer should avoid long PCB traces and component leads. Compensation and filter components should be located near the FAN400A. Finally, increasing the power-MOS gate resistance is advised.
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Applications Information
Figure 16.
Reference Circuit (without Secondary-Side Feedback)
BOM
Reference
BD1 CX1 (Option) CY1 (Option) C1 C2 C3 C4 C7 (Option) C8 C9 D1 D2 D4 D5 (Option)
Component
BD DI106 1A/600V YC 4.7nF/400V (Y1) YC 2.2nF/250V (Y1) EC 4.7F/400V 105C EC 4.7F/400V 105C CC 1nF/1kV EC 10F/50V CC 1nF/100V 1206 EC 470F/10V 105C EC 220F/10V 105C Diode FRI07 Diode FR102 Diode SB360 ZD 6.8V/0.5W F1 L1 L2
Reference
R 1/0.5W
Component
Inductor 20mH 6*8mm Inductor 10H 6mm MOSFET 1A/600V R 750k/1206 R 47k/1206 R 47/1206 R 4.7/0.5W R 100/0805 R 10/1206 R 10/1206 Transformer EE-16 IC FAN400A (Green PWM IC)
Q1 R1,R2 R3,R4 R5 R6 R7 R8 R10 (Option) T1 U4
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Applications Information (Continued)
Figure 17.
Reference Circuit (with Secondary-Side Feedback)
BOM
Reference
BD1 CY1 (Option) C1 C2 C3 C4 C6 C7 (Option) C8 C9 C10 D1 D2 D4 D5 (Option) F1 L1
Component
BD DI106 1A/600V YC 2.2nF/250V (Y1) EC 4.7F/400V 105C EC 4.7F/400V 105C CC 1nF/1kV EC 10F/50V CC 4.7nF/0805 CC 1nF/100V 1206 EC 470F/10V 105C EC 470F/10V 105C CC 2.2nF/0805 Diode FRI07 Diode FR102 Diode SB360 ZD 6.8V/0.5W R 1/0.5W Inductor 20mH 6*8mm L2
Reference
Q1 R1,R2 R3,R4 R5 R6 R7 R8 R10 R11 R12 R13 R14 T1 U1 U2 U3
Component
Inductor 10H 6mm MOSFET 1A/600V R 750k/1206 R 47k/1206 R 47/1206 R 4.7/0.5W R 100/0805 R 10/1206 R 10/1206 R 100/ 1/8W R 33k/0805 R 33k/ 1/8W R 4.7k/0805 Transformer EE-16 IC FAN400A (Green PWM IC) IC PC817 IC TL431
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Physical Dimensions
9.83 9.00
6.67 6.096
8.255 7.61
5.08 MAX
3.683 3.20
7.62
0.33 MIN (0.56) 2.54
3.60 3.00 0.56 0.355 1.65 1.27
7.62
0.356 0.20 9.957 7.87
NOTES: UNLESS OTHERWISE SPECIFIED A) THIS PACKAGE CONFORMS TO JEDEC MS-001 VARIATION BA B) ALL DIMENSIONS ARE IN MILLIMETERS. C) DIMENSIONS ARE EXCLUSIVE OF BURRS, MOLD FLASH, AND TIE BAR EXTRUSIONS. D) DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994 E) DRAWING FILENAME AND REVSION: MKT-N08FREV2.
Figure 18. 8-Pin Dip-8 Package
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild's worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor's online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/.
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1 www.fairchildsemi.com 13
FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
Physical Dimensions (Continued)
Figure 19.
6-Pin SSOT-6 Package
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild's worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor's online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/.
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1 www.fairchildsemi.com 14
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FAN400A -- Low-Power Green-Mode PWM Flyback Power Controller without Secondary Feedback
(c) 2008 Fairchild Semiconductor Corporation FAN400A Rev. 1.0.1
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